A key-value map specifying response parameters that are passed to the method response
from the back end. The key is a method response header parameter name and the mapped
value is an integration response header value, a static value enclosed within a pair
of single quotes, or a JSON expression from the integration response body. The mapping
key must match the pattern of method.response.header.{name}, where name
is a valid and unique header name. The mapped non-static value must match the pattern
of integration.response.header.{name} or integration.response.body.{JSON-expression},
where name is a valid and unique response header name and JSON-expression
is a valid JSON expression without the $ prefix.

Specifies the regular expression (regex) pattern used to choose an integration response
based on the response from the back end. For example, if the success response returns
nothing and the error response returns some string, you could use the .+
regex to match error response. However, make sure that the error response does not
contain any newline (\n) character in such cases. If the back end is
an AWS Lambda function, the AWS Lambda function error header is matched. For all other
HTTP and AWS back ends, the HTTP status code is matched.